The campaign of Democrat Julie Lassa is hitting the U.S. Chamber of Commerce for what it calls a "vicious TV ad campaign" that Lassa says displays her home phone number.  

In the spot, the Chamber displays a phone number above the words, "Tell Julie Lassa, stop voting for job-killing tax hikes."

The number in question appears on Lassa's member page on the website of the Wisconsin State Legislature, where it's labeled "District Number." The Hill confirmed the number is in fact Lassa's home phone number, but the Chamber maintains it's labeled as the number to her district office.   

The Lassa campaign does admit that the number is publicly available, citing Lassa's reputation for constituent service as a state senator. But Lassa campaign manager Rick Fromberg said using the number in an attack ad is "way beyond the bounds of common decency."

"This has been a serious breach of her family's security and peace of mind," Fromberg said. 

Lassa is locked in a tight race with Republican Sean Duffy in the open-seat contest to succeed retiring Rep. David Obey (D). The race has garnered national attention from both parties' congressional campaign committees and plenty of ad spending from outside groups. 

The Lassa camp is calling on Duffy to publicly denounce the ad and refuse any further assistance from the Chamber, which the campaign also hit for using "foreign funding to try and influence elections."

It's an attack against the business lobby that Democrats have ramped up this week, with Democrats in competitive House and Senate contests across the country denouncing the Chamber's role in the 2010 elections and questioning the group's sources of funding. 

Duffy's campaign said its candidate has been calling on Lassa to denounce what he calls false attacks leveled at him by third-party groups.  

"The better number to call Sen. Lassa at about her horrible, anti-job record is her campaign office at 715-344-8222," said Duffy campaign spokeswoman Wendy Riemann.